1. Field of the Invention
This invention relates to structures and methods for fabricating perpendicular write heads. More specifically, the invention relates to structures and methods for fabricating wrap around and trailing shields using metal capped seed layers prior to shield plating.
2. Description of the Related Art
Perpendicular write heads are currently well known in the art. Variants of such heads, having wrap around shields and trailing shields, have been recently disclosed. See, for example US Patent Application Publications 2005/0259355, 2006/0044682 and 2006/0174474, assigned to Hitachi Global Storage Technologies, Netherlands B.V.
During the fabrication of the wrap around shield of the prior art, a film stack containing the magnetic pole material, a non-magnetic gap layer, a CMP stop layer, and a number of image transfer layers are deposited. After the pole width is imaged and the film stack etched by a number of consecutive etch processes, a film stack containing the tapered pole material is created. A conformal non-magnetic layer is then deposited, which will serve as the side shield or wrap around shield gap material. Following deposition of the side gap material, a layer of RI-etchable material is deposited and the structure planarized by CMP. Following planarization, the RIE etchable material is removed leaving the tapered pole, main gap and side gap materials. A magnetic material is then deposited over this structure by electroplating to form the wrap around shield. Prior to plating, a conductive seed layer is deposited to provide a starting cathode for the plating process. Subsequent to seed layer deposition, a blanket photo resist layer is deposited. This layer is imaged and developed to provide a plating mask for the shield.
During the formation of trailing shields of the prior art, a film stack containing the magnetic pole material, a non-magnetic gap layer, a CMP stop layer, and a number of image transfer layers are deposited. The pole width is imaged and the film stack etched by a number of consecutive etch processes, creating a film stack containing the tapered pole material. A filler layer is deposited and the resulting structure planarized by CMP to the stop layer. A plating seed layer is subsequently deposited, followed by processes to make the photo resist plating mask.
Typically, Rh or NiCr seed layers are used in the prior art for both wrap around and trailing shield deposition. Rh seed layers may exhibit adhesion problems to the photo resist layer deposited over them, resulting in under-plating (plating of the shield under the photo resist) and photo resist failures. For the case of NiCr seed layers, these may oxidize prior to immersion in the plating bath, causing poor adhesion of the plated shield. The oxides formed on these seed layers are not easily removed by the plating bath chemistry. The photo resist adhesion problem to Rh seed layers can be mitigated by using an inorganic SiN based ARC (anti-reflection coating), but a separate RIE step is required to remove this coating prior to plating, which can damage the developed photo resist mask, detrimentally affecting critical dimension control.
What is needed is a better process for producing the warp around and trailing shields for the perpendicular write head.
United States Patent Application Publication 2006/0174474 discloses a mask structure for fabricating a write pole for a perpendicular write head. The mask structure includes a first and second hard mask structures separated by an image transfer layer, such as DURAMIDE. The first mask structure may be a bi-layer mask structure that functions as a CMP stop as well as a hard mask for ion milling. The first hard mask is chosen to have a desired resistance to removal by ion milling to maintain excellent track width control during an ion milling process used to form the write pole. Therefore, the first hard mask may be comprises of two layers selected from the group consisting of Rh, alumina, and diamond like carbon (DLC). The second hard mask is constructed of a material that functions as a bottom antireflective coating as well as a hard mask.
United States Patent Application Publication 2006/0044682 discloses a write element for use in perpendicular magnetic recording. The write element including a write pole and a self aligned wrap around shield that can have a trailing shield gap thickness that is different from its side shield gap thickness. The materials making up the trailing shield gap and the side shield gaps can be different materials or can be the same material deposited in two different steps. The side or wrap around portions of the trailing shield can extend down to the level of the leading edge of the write pole or can terminate at some point between the levels of the leading and trailing edge to form a partial wrap around trailing shield.
United States Patent Application Publication 2005/0239001 discloses methods of forming a component of a thin film magnetic head and improving the plating of a component of a thin film magnetic head. The methods include the use of a high activation energy chemically amplified photoresist (CARS) that is contacted with a low pH high saturation magnetic moment plating solution to form a magnetic head component that is essentially free of plating defects. The methods find utility in hard disk drive applications, such as in the manufacture of magnetic poles for the write head of a hard disk drive.
United States Patent Application Publication 2005/0259355 discloses a perpendicular write head including a main pole and a trailing shield, the main pole being made of a diamond-like carbon (DLC) layer as hard mask and a rhodium (Rh) layer as shield gap, both DLC and Rh layers being CMP stop layers so as to avoid corner rounding and damage from chemical mechanical planarization (CMP) process, the DLC layer being removed by reactive ion etching (RIE) to create a trench, the trailing shield being deposited into the trench for self alignment.
United States Patent Application Publication 2005/0068671 discloses a magnetic transducer with separated read and write heads for perpendicular recording. The write head has a trailing shield that extends from the return pole piece toward the main pole piece to form the write gap at the air-bearing surface. One embodiment of the trailing shield is a two part structure with a pedestal and a much smaller tip that confronts the main pole piece at the gap. In one embodiment a sink of non-magnetic, electrically conductive material is disposed in the separation gap between the read head and the flux bearing pole piece. The sink is preferably made of copper and does not extend to the ABS.
United States Patent Application Publication 2004/0264066 discloses at both end portions of at least a soft magnetic layer of a magneto-resistive effect film, a pair of bias magnetic field applying layers are disposed for applying a longitudinal bias magnetic field to the soft magnetic layer via magnetic underlayers. Further, mutual lattice point-to-point distances in the plane where each magnetic underlayer and the corresponding bias magnetic field applying layer are mated, are substantially equalized to each other. Therefore, a coercive force Hc in an in-plane direction (direction parallel to a film surface) of each bias magnetic field applying layer can be maintained at a high level so that even when further gap narrowing or track narrowing is aimed, the bias magnetic field applying layers can act to apply an effective bias magnetic field, i.e. can act to suppress occurrence of the Barkhausen noise.
U.S. Pat. No. 7,097,923 discloses a tri-layer anti-reflective coating for use in photolithographic applications, and specifically, for use in ultraviolet photolithographic processes. The tri-layered anti-reflective coating is used to minimize pattern distortion due to reflections from neighboring features in the construction of microcircuits. The tri-layer anti-reflection coating features a first layer, a first dielectric layer, an absorption layer disposed on the first dielectric layer, and a second dielectric layer, which is then disposed between the absorption layer and a photoresist layer. At least the absorption layer and dielectric layers can be formed using vacuum deposition. A unique character of the tri-layer anti-reflective coatings is that it dampens reflections structures having severe topologies and also allows a thinner anti-reflection layer that has a wider process latitude.
U.S. Pat. No. 6,912,106 discloses a method and system for providing a recording head is disclosed. The method and system include providing a first pole, a second pole, a write gap and at least one coil. The write cap separates the first pole from the second pole. The coil(s) include a plurality of turns and is between the first and second poles. The first pole includes a pedestal that has a first portion and a second portion. The first portion includes a high moment electroplated material. The second portion includes a hot seed layer that has a high moment sputtered material. The second portion of the first pole is adjacent to the write gap.
U.S. Pat. No. 6,876,507 discloses a thin-film write head employing pole pieces formed of an electroplated body-centered cubic (BCC) nickel-iron alloy with a saturation flux density (BS) of 1.9 to 2.3 T (19 to 23 kG) and an acceptable coercivity (HC) of about 80 to about 160 A/m (1-2 Oe). The iron content of the electroplated nickel-iron alloy is from 64% to 81% by weight. The two-layer pole fabrication process holds magnetic anisotropy and coercivity to useable values while improving saturation flux density and optimizing magnetostriction. This is accomplished by first electroplating a BCC nickel-iron layer onto an underlying seed layer and then annealing the two layers to reduce coercivity to less than about 160 amps/meter and raise magnetization to acceptable levels.